diff --git a/src/wp-admin/custom-header.php b/src/wp-admin/custom-header.php
index e61feb781c..ba9bb72dd4 100644
--- a/src/wp-admin/custom-header.php
+++ b/src/wp-admin/custom-header.php
@@ -683,8 +683,13 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 	 */
 	public function step_2() {
 		check_admin_referer('custom-header-upload', '_wpnonce-custom-header-upload');
-		if ( ! current_theme_supports( 'custom-header', 'uploads' ) )
-			wp_die( __( 'Cheatin’ uh?' ), 403 );
+		if ( ! current_theme_supports( 'custom-header', 'uploads' ) ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1>' .
+				'<p>' . __( 'The current theme does not support uploading a custom header image.' ) . '</p>',
+				403
+			);
+		}
 
 		if ( empty( $_POST ) && isset( $_GET['file'] ) ) {
 			$attachment_id = absint( $_GET['file'] );
@@ -834,11 +839,21 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 	public function step_3() {
 		check_admin_referer( 'custom-header-crop-image' );
 
-		if ( ! current_theme_supports( 'custom-header', 'uploads' ) )
-			wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+		if ( ! current_theme_supports( 'custom-header', 'uploads' ) ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1>' .
+				'<p>' . __( 'The current theme does not support uploading a custom header image.' ) . '</p>',
+				403
+			);
+		}
 
-		if ( ! empty( $_POST['skip-cropping'] ) && ! ( current_theme_supports( 'custom-header', 'flex-height' ) || current_theme_supports( 'custom-header', 'flex-width' ) ) )
-			wp_die( __( 'Cheatin&#8217; uh?' ), 403 );
+		if ( ! empty( $_POST['skip-cropping'] ) && ! ( current_theme_supports( 'custom-header', 'flex-height' ) || current_theme_supports( 'custom-header', 'flex-width' ) ) ) {
+			wp_die(
+				'<h1>' . __( 'Cheatin&#8217; uh?' ) . '</h1>' .
+				'<p>' . __( 'The current theme does not support a flexible sized header image.' ) . '</p>',
+				403
+			);
+		}
 
 		if ( $_POST['oitar'] > 1 ) {
 			$_POST['x1'] = $_POST['x1'] * $_POST['oitar'];